Obesity, a chronic disease, is caused by many factors, but its origin has not been clear so far. Obesity is also an inducing factor to a series of diseases, such as hypertension, diabetes, coronary heart disease, gallbladder disease, osteoarthritis, sleep apnea, respiratory disorder, hysteroma, prostate cancer, breast cancer and colon cancer. It is reported by NIH that there are about 97 million Americans are overweight or over-fat, in which about 15.1 million people suffer from obesity-related type II diabetes, and about 200,000 people die from obesity-related diseases each year.
Obesity is generally caused by excess body fat due to functional changes in physiology or biochemistry. Fat usually includes neutral lipids, phospholipids and cholesterol. Fat increase is due to more energy intake over energy consumption. In terms of pathogenesis, obesity includes two types: (a) simple obesity and (b) secondary obesity. The simple obesity can be divided into idiopathic obesity and acquired obesity, and the number of patients with the simple obesity can account for more than 95% of the total number of patients with obesity. Idiopathic obesity is caused by tremendous adipocytes, and is common in childhood obesity. Acquired obesity is caused by adipocytes in larger size and is common in adult obesity. Secondary obesity, also known as symptomatic obesity, is usually caused by endocrine or metabolic diseases.
At present, there are five strategies for the treatment of obesity: dieting, exercising, behavioral therapy, medical therapy, and therapeutic operation, which strategy or strategies combination is selected primarily depending on health risk factors and the rate and effect of weight loss of a patient. The rate and effect of weight loss of the patient are affected by many factors, such as age, height, family history and risk factors. Diet-exercise therapy, i.e. diet with food with low calorie and low fat in combination with aerobic exercise, needs to be insisted for a long term, is generally considered unsuccessful to general public, however. Surgery for removal of body fat can achieve immediate results, but with many restrictions, such as operation risk, non-persistent effect and high expensive cost.
Presently, medical therapy is the main clinical method for treating obesity and obesity-related diseases (such as diabetes). Mechanisms of medical therapy include appetite suppression, increasement of energy consumption, stimulation of fat movement, reduction of triglyceride synthesis and inhibition of fat absorption. Currently, drugs mainly include: phenylpropanolamine (PPA), orlistat (Xenical III) and sibutramine (Reductil™). Hyperglycemia in some diabetics still cannot be adequately controlled by the diet and/or exercise therapies or use of the above-described therapeutic compounds. For these patients, exogenous insulin should be used, which is not only very expensive and painful, but also will bring about a variety of complications to patients. For example, error calculation to insulin dose caused by lack of food and abnormal exercise will lead to insulin response (hypoglycemia). In addition, use of drugs may also give rise to local or systemic allergies or immune resistance to drugs.
At present, there is no effective method and medicament for treating or preventing obesity and related diseases thereof with fewer side-effects in the related art. Therefore, it is urgently needed in the art to develop a new medicament for treating or preventing obesity and related diseases thereof without toxic side effect.